American Chemical Society
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Ethylene Polymerization Catalysis by Vanadium-Based Systems Bearing Sulfur-Bridged Calixarenes

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posted on 2011-11-14, 00:00 authored by Carl Redshaw, Lucy Clowes, David L. Hughes, Mark R. J. Elsegood, Takehiko Yamato
Calixarenes bridged by thia (−S−), sulfinyl (−SO−), or sulfonyl (−SO2−) linkers have been employed as ancillary ligands in vanadium-based ethylene polymerization and in the ring-opening polymerization of ε-caprolactone. For ethylene polymerization, all pro-catalysts [PPh4]­[VOCl2(R-calix­[4]­areneH2)] (R = p-tert-butylthia (−S−) (1), sulfinyl (−SO−) (2), sulfonyl (−SO2−) (3)) were highly active, with the system bearing the sulfonyl (−SO2−)-bridged calixarene displaying enhanced activity. The molecular structures of pro-catalysts 2 and 3 are reported. Pro-catalysts 13 were inactive for the ROP of ε-caprolactone.